Makasitomala ambiri amafunsa posankha achopatsira kanema wovuta- pali kusiyana kotani pakatiCOFDM mavidiyo opanda zingwendi OFDM kanema transmitter?
COFDM ndi Coded OFDM, Mubulogu iyi tikambirana kuti tikuthandizeni kudziwa kuti ndi njira iti yomwe ingakhale yabwino kugwiritsa ntchito kwanu.
1. OFDM
Tekinoloje ya OFDM imagawa njira yoperekedwa m'njira zambiri za orthogonal mu frequency domain.Chonyamulira chimodzi chimagwiritsidwa ntchito posinthira pa subchannel iliyonse, ndipo chonyamulira chilichonse chimafalikira mofanana.Mwanjira iyi, ngakhale njira yonseyo sikhala yosalala komanso yosankha pafupipafupi.Koma subchannel iliyonse imakhala yosalala.Kutumiza kwa Narrowband kumachitidwa pa kanjira kakang'ono kalikonse, ndipo bandwidth ya chizindikiro ndi yaying'ono kuposa bandwidth yofananira ya njira.Chifukwa chake, kusokoneza pakati pa ma waveform azizindikiro kumatha kuthetsedwa kwambiri.
Popeza onyamula kanjira kakang'ono kalikonse amakhala ogwirizana munjira ya OFDM.Mawonekedwe awo amaphatikizana.Izi sizimangochepetsa kusokonezana pakati pa zonyamulira zazing'ono, komanso zimathandizira kugwiritsa ntchito ma spectrum.
2. COFDM
Mtengo wa COFDMis Coded Orthogonal Frequency Division Multiplexing, kutanthauza
kusinthidwa kwa OFDM kusanachitike, mayendedwe a digito amasungidwa.
Kodi Coded iyi imachita chiyani?Ndikolemba mayendedwe (kulembera gwero ndikuthana ndi vuto lakuchita bwino, ndipo kuyika tchanelo ndikuwonetsetsa kudalirika kwa kufalitsa).
Njira yeniyeni ndi:
2.1.Kuwongolera Kolakwika Patsogolo (FEC)
Mwachitsanzo, ma bits 100 a data amafunika kusinthidwazakutumizandi.Choyamba sinthani kukhala ma bits 200,.Chizindikiro chikalandiridwa, ngakhale patakhala vuto ndi kutumiza ma bits 100, deta yolondola imatha kuchotsedwabe.Mwachidule, ndikuwonjezera redundancy musanayambe kusinthasintha kuti muthe kudalirika kwa kufalitsa.Izi zimatchedwa Internal Error Correction (FEC) mu COFDM systems.Ndipo it ndi gawo lofunikira la COFDM system.
2.2.Guard Interval
Fkapena cholinga cha solvndizambiri-vuto lanjirakutichizindikiro chopatsirana chimafika pamapeto olandila kudzera munjira zingapo zotumizira. Anthawi yachitetezo imayikidwa pakati pa ma data omwe amatumizidwa.
3.Mapeto
Kusiyana pakati pa COFDM ndi OFDM ndikuti ma code owongolera zolakwika ndi nthawi za alonda amawonjezedwa musanayambe kusintha kwa orthogonal kuti kufalitsa kwa siginecha kukhale kothandiza kwambiri.
OFDM imathetsa kusanja kwa tchanelo mumitundu yambiri-njira chilengedwe bwino, koma sanagonjetse njira lathyathyathya kuzimiririka.
COFDM imathandizira kuzimiririka kwa siginecha yamtundu uliwonse panthawi yopatsirana kuti iwoneke ngati yodziyimira pawokha kudzera pamakhodi, potero amachotsa chikoka cha kuzimiririka kosalekeza komanso kusintha kwafupipafupi kwa Doppler.
4.Kugwiritsa ntchito OFDM ndi COFDM
COFDM ndiyabwino kwambiri kufalitsa opanda zingwe nthawiliwilo lalikulukusuntha.Monga Hd wwopanda ntchitotransmittervehiclemkunja, zombokulumikizana kwa mesh, ma helikoputalaCofdm Hd Transmitter ndiluwurangedronevlingalirotransmitter.
COFDM ilinso ndi luso lamphamvu la nlos.Ndioyenera kugwiritsidwa ntchito m'malo osawoneka komanso otsekeka monga madera akumidzi, madera ozungulira, ndi nyumba, ndipo amawonetsa kuthekera kwakukulu kwa "kusokoneza" ndi "kulowa".
OFDM imathandizira kugwiritsa ntchito bwino ma sipekitiramu ndipo imatha kugonjetsedwa ndi kutha kosankha pafupipafupi, komwe kumagwiritsidwa ntchito nthawi zonse mu LTE ndi netiweki ya wifi.
Nthawi yotumiza: Jun-12-2023
